1. Field of the Invention
The present invention relates to a pressure sensor device having a breakable mounting member, the sensor device being used in moving vehicles such as automobiles, vessels or airplanes, or in stationary apparatus such as a home gas supplier.
2. Description of Related Art
A pressure sensor device installed in an automobile vehicle for measuring gasoline vapor pressure in a gasoline tank is known hitherto. Generally, this kind of pressure sensor device is composed of a sensor portion for sensing the vapor pressure and an inlet port for introducing the vapor pressure into the sensing portion. In the conventional pressure sensor, the inlet port is connected to a conduit connecting a gasoline tank and a canister for absorbing gasoline vapor. In case the vehicle crashes in accident, the inlet port may be broken.
in consideration of such an accidental breakage of the inlet port of the pressure sensor device, a sensor device shown in FIG. 16 has been proposed and put in the market. The pressure sensor device 200 is composed of a sensor portion 201 having a semiconductor diaphragm pressure-sensitive element 201a and an inlet port portion 202 for introducing gasoline vapor pressure into the sensor portion 201 along a path shown with an arrow "A." The pressure sensor portion 201 and the inlet port portion 202 are connected by a narrowed portion 202a. At a bottom end of the inlet port portion 202, a check valve 202b is installed. The narrowed portion 202a breaks off, separating the sensor portion 201 from the inlet port portion 202, in case the vehicle crashes with a impact higher than a predetermined level (e.g., 30 G). In this instance, atmospheric pressure is introduced into the inlet port, and thereby the check valve 202b is closed to prevent the gasoline vapor from entering the inlet port. Thus, the gasoline vapor is prevented from being introduced into the sensor device in case an accident occurs. However, the conventional device has to include the narrowed portion 202a and the check valve 202b to attain the purpose. Accordingly, the structure of the device becomes complex and the device becomes large in size.